A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-00-222-7749
NSN 6610-00-681-0590
NSN 5855-01-222-0992
NSN 5945-01-490-3391
NSN 6240-00-079-0112
NSN 6650-01-237-3334
NSN 5915-01-274-0587
NSN 6150-01-421-8840
NSN 5965-01-549-9943
NSN 7035-00-215-3272
NSN 6320-00-636-0922
NSN 6135-00-078-9931